Tri-cylinder lock



April 3, 1962 MOORE TRI-CYLINDER LOCK Filed Feb. 2, 1960 IN VEN TOR.

LLOYD L. MOORE ATTOR N EYS United States Patent (I) 3,027,744 TRI-CYLINDER LOCK Lloyd L. Moore, 2107 NE. Union Ave., Portland, Oreg. Filed Feb. 2, 1960, Ser. No. 6,205 4 Claims. (Cl. 70134) This invention relates to a door lock, and more particularly to a door lock which includes three locking cylinders. A primary object of this invention is the provision of a look which includes the customary inner and outer cylin der for locking or unlocking the door, and a third cylinder which is so arranged that it may be employed only to lock, but not to unlock the door. The invention is particularly useful in those cases where it is desired to give an em ployee or custodian a key in order to lock the door when he leaves, but not to permit him to reenter the premises by the use of the same key after the door has once been locked. By means of this lock a multitude of keys can be issued, and even in the event the keys are lost or stolen or given to unreliable employees they are useless to unlock the door, since their only function is to lock the same.

An additional object of the invention is the provision of such a tri-cylinder lock which may be readily adapted to conventional doors, with a minimum of effort and difficulty.

Still another object of the invention is the provision of an arrangement of this type which may be applied to the standard lock with a minimum amount of modification of the operating parts thereof.

A still further object of the invention is the provision of a lock of this character which is sturdy and durable in construction, reliable and eflicient in operation, and relatively simple and inexpensive to manufacture, assemble and utilize.

Still other objects will in part be obvious, and in part be pointed out as the description of the invention proceeds, and shown in the accompanying drawing wherein there is disclosed a preferred embodiment of this inventive concept.

In the drawing:

FIGURE 1 is a side sectional view taken through one form of lock embodying the elements of the instant invention, the lock being shown in locked position.

FIGURE 2 is a sectional view taken substantially along the line 22 of FIGURE 1 as viewed in the direction indicated by the arrows.

FIGURE 3 is a fragmentary view similar to FIGURE 1, but showing certain of the operative parts in a different position of adjustment.

Similar reference characters refer to similar parts throughout the several views of the drawing.

Having reference now to the drawings in detail there is generally indicated at a lock assembly in accordance with the instant invention, which is adapted to be positioned in a door 11, or the like. The lock assembly 10 includes a central housing 12, which is provided in conventional manner with inner and outer lock cylinders 13 and 14. Each of the cylinders 13 and 14 is provided with a locking arm 15 and 16, respectively, which, when actuated by a key are adapted to engage a transverse member 17, which comprises an integral part of the locking bolt 18. Pivotally mounted on the locking bolt, in a known manner, is av locking arm 19, which is spring biased to the position as shown in FIGURE 1 by means of a spring connected thereto and to the locking bolt 18. The locking arm is provided with a projection 21, which engages a dog 22 which is fixed to the lock housing, the arrangement being such that unless the projection 21 is moved downwardly to clear the dog 22, bolt 18 may not be moved in either direction, this disengagement of the lug 21 from the dog 22 being the first function of the locking lever 15 or 16. The locking arm 19 carries a 3,027,744 Patented Apr. 3, 1952 transverse bar 23 which is adapted to be engaged selectively by one or the other of locking levers 15 or 16 for the purpose of depressing the same, prior to movement of the locking bolt itself.

The above described arrangement is largely conventional, as is the guide roller 24 on the lower end of the bolt, which engages the housing for supporting the bolt in suitable aligned position.

The device of the instant invention comprises a third lock cylinder 25 which is operated by a key which is different from the key which operates lock cylinders 13 and 14, and which includes a locking lever 26. This lock is adapted only for locking the door, and cannot be employed for unlocking the same after it is once locked.

In accordance with the instant invention there is provided on the inner end wall of lock housing 12 a slide member 27, which is slotted for the reception of studs 28, so that the same may slide vertically. An inwardly extending tongue 29 is adapted to engage over a rearwardly extending tip 30 of the locking arm 19, when the bolt 13 is moved to unlocked position as shown in FIGURE 3. Movement of locking lever 26 causes the depression of an arcuate arm 31 integral with the slide 27, which is spring biased upwardly by means of a coil spring 32, so as to disengage the lug 21 from the dog 22, so that the bolt 18 may, by continued movement of locking lever 26, be moved from the position of FIGURE 3 to the locked position shown in FIGURE 1. This is afiected by the engagement of the locking lever 26 with a projection 33 on the lower part of the bolt 18, which is efiective to cause the bolt 18 to move to locked position. However, once the bolt has been so moved, the tip 30 is disengaged from beneath the tongue 29, so that the key of cylinder 25 is no longer effective to draw the locking arm 19 downwardly into such position that the bolt may be moved to unlocked position.

It will accordingly be seen that the arrangement is such that the lock cylinder 25 is operable only to move the bolt to locked position, but in the event that any attempt is made to unlock the bolt by means of the cylinder 25, the key will turn futilely since there are no parts in a position to be engaged by the locking lever 26.

From the foregoing, it will now be seen that there is herein provided an improved tri-cylinder lock, which accomplishes all the objects of this invention, and others, including many advantages of great practical utility and commercial importance.

As many embodiments may be made of this inventive concept, and as many modifications maybe made of the embodiment hereinbefore shown and described, it is to be understood that all matter herein is to be interpreted merely as illustrative and not in a limiting sense.

I claim:

1. A lock having an inner and an outer lock cylinder both operable by a first key, each of said cylinders including a locking lever, a locking bolt having a locking arm pivotally mounted thereon, dog means normally in engagement with said locking arm to prevent movement of said locking bolt, said locking arm engageable by either of said locking levers to pivot the same out of engage ment with said dog means to allow said locking bolt to be moved to locked and unlocked positions by said locking levers when actuated by means of said first key inserted in either lock cylinder, a slide member, said locking arm being in engagement with said slide member when said locking bolt is in an unlocked position, a third lock cylinder operable by a second key, said third lock cylinder having a locking lever engageable with said slide member to move the same to move said locking arm out of engagement with said dog means when the locking bolt is in unlocked position, said third locking cylinder being operable by said second key to move its locking lever to J engage said locking bolt to move the same from an unlocked to locked position only.

2. In combination with a lock having an inner and an outer lock cylinder, each having a locking lever, and a locking bolt moveable to locked and unlocked position by either of said locking levers by means of a key inserted in either lock cylinder, a third cylinder having a locking arm operable by a diiferent key effective only to move said bolt from unlocked to locked position but not from locked to unlocked position, said bolt having an arm pivoted thereto, a projection on said arm, a fixed dog normally engageable by said projection, said locking levers of said first and second cylinders being operable to disengage said projection from said dog, said bolt being moveable only when said projection is disengaged from said dog, a slidable member adjacent the free end of said arm and engageable by said free end of said arm when said bolt is in unlocked position, means on said slidable lember engageable by the locking arm on said third cylinder to move said slidable member and hence said arm to disengage said projection from said dog, and a lug on said locking bolt engageable by said locking lever on said third cylinder to move said bolt to locked position, movement of said bolt to locked position releasing said free end of said arm from said slidable member whereby disengagement of said projection from said dog may be affected again only by movement of said locking arm of said first or second cylinder.

3. In combination with a lock having an inner and an outer lock cylinder, each having a locking lever, and a locking bolt moveable to locked and unlocked position by either of said locking levers by means of a key inserted in either lock cylinder, a third cylinder having a locking arm operable by a difierent key effective only to move said bolt from unlocked to locked position but not from locked to unlocked position, said bolt having an arm pivoted thereto, a projection on said arm, a fixed dog normally engageable by said projection, said locking levers of said first and second cylinders being operable to disengage said projection from said dog, said bolt being moveable only when said projection is disengaged from said dog, a slidable member adjacent the free end of said arm and engageable by said free end of said arm when said bolt is in unlocked position, means on said slidable member engagea'ole by the locking arm on said third cylinder to movesaid slidable member and hence said arm to disengage said projection from said dog, and a lug on said locking bolt engageable by said locking lever on said third cylinder to move said bolt to locked position, movement of said bolt to locked position releasing said free end of said arm from said slidable member whereby disengagement of said projection from said dog may be allected again only by movement of said locking arm of said first or second cylinder and spring means normally biasing said slidable member to a position to be engaged by said free end of said arm.

4. The structure of claim 3 wherein said means on said slidable member engageable by the locking arm of said third cylinder comprises a downwardly extending integral arcuate projecting arm.

References Cited in the file of this patent UNITED STATES PATENTS 1,004,729 Bassick et al Get. 3, 191] 1,232,035 Hurd July 3, 1917 2,016,687 Sprecker Oct. 8, 1935 2,936,606 Welch et al May 17, 1960 

